Typically, interconnects for Integrated Circuits (IC) are formed by windows through a passivation layer on the chip to facilitate an electrical connection to the active circuitry in the chip. The passivation layer is typically a layer of nonconductive oxide or other dielectric material that serves to isolate the circuitry of the chip from the outside world. The number of windows in the passivation layer is dictated by the functionality of the chip. For a typical radio-frequency identification (RFID) chip the number of active interconnections is two. These interconnections facilitate the attachment the terminals of the antenna of the RFID circuit to the chip circuitry. A diagram of a typical chip and interconnection location of an RFID chip is given in FIG. 1. Typical RFID IC chips are 1 mm square with bond pads being 20 microns square.
In a typical RFID application, metallic bumps are formed on the interconnections, these are typically slightly larger than the interconnects in the plane of the IC and typically 10-20 microns high (out of the plane of the IC). The interconnect bumps may be formed of gold, nickel, copper, solder or other metal. The composition of the interconnect bumps and methodologies for the fabrication are known to those skilled in the art.